1. Field of the Invention
The present invention relates to a golf club head with a polymer insert. More specifically, the present invention relates to a golf putter head with a polymer insert.
2. Description of the Related Art
Throughout the history of golf, which dates back to as early as 1457, various techniques have been used to enhance the hitting characteristics of golf club heads. Golf club heads having inserts for the striking portion have been used at least as far back as 1880""s when leather face irons were manufactured in Scotland. Golfer""s in the 1890""s were able to purchase putters with faces composed of gutta percha. More recently, inserts composed of various materials and shapes have been put forth by the creative geniuses of the golf industry to provide golfers with better feel and control of the golf ball.
One example is an ODYSSEY(copyright) putter having a STRONOMIC(copyright) insert that is disclosed in Magerman et al., U.S. Pat. No. 5,575,472 for a Golf Putter Head Having Face Insert And Method Of Forming The Same. The Magerman et al. Patent discloses a putter head with a recess into which is poured or inserted a resinous material which cures and is subsequently milled to produce the putter.
Another example is Pond, U.S. Pat. No. 5,524,331 for a Method For Manufacturing Golf Club Head With Integral Inserts that discloses a method for casting a graphite-epoxy composite insert within a recess of a face of a metal club head. The golf club head of the Pond Patent is directed at displacing the weight away from the center and increasing the moment of inertia.
Another example is Schmidt et al., U.S. Pat. No. 5,485,997, for a Golf Putter Head With Face Plate Insert Having Heightened Medial Portion, that discloses a putter head with a face plate composed of a non-metallic material such as an elastomer. The overall construction of the putter head of the Schmidt et al. Patent is directed at enlarging the sweet spot and improving the peripheral weighting.
Yet another example is found in Baker et al., U.S. Pat. No. 5,931,743 for a Putter Having Club Head With A Golf-Ball Engagement Insert And A Shaft Rearwardly Of The Insert which discloses a putter with a center shaft and an insert composed of a thermoplastic polyurethane. Another example is Jepson et al., U.S. Pat. No. 3,937,474 for a Golf Club With Polyurethane Insert, which discloses a wood having an insert on its striking face that is composed of a polyurethane formed from a toluene diisocyanate polyether terminated prepolymer and a curing agent. The hardness of this insert varies from 40 to 75 shore D, and a Bayshore Resiliometer of 1 7 or above. The polyurethane insert is claimed to impart additional energy to the golf ball during a golf hit.
Chen et al., U.S. Pat. No. 5,743,813 for a Golf Club Head discloses a wood composed of stainless steel with a three layer face having a first stainless steel layer, an elastic layer and a second stainless steel layer. The three-layer face does not absorb the hitting force when a golf ball is hit.
Fisher, U.S. Pat. No. 5,458,332, for a Golf Putter Head With A Cushioning Face, discloses a set of golf putters, each having an insert composed of polyurethane with a hardness in the range of 70 Shore A to about 80 Shore D. The rebound factor of each of the inserts is in the range of 12.5% to 50%, and the inserts are formulated to effect a reproducible direct linear relationship between the rebound factor and the distance of the putt.
Yet another example is McGeeney et al, European Patent Application Number 0891790 for a Multiple Density Golf Club Head And Method Of Manufacturing which discloses a putter with a central segment composed of a thermoplastic elastomer or a thermoset polymer. Possible thermoplastic elastomers include styrene co-polymers, co-polyesters, polyurethanes, polyamides, olefins and vulcanates. Possible thermoset polymers include epoxides, polyimides and polyester resins. The central segment has a minimum durometer hardness of Shore D 50. The central segment is bounded by metallic heel and to portions. However, the use of inserts is restrained in order to maintain the integrity of the game of golf.
In this regard, the Rules of Golf, established and interpreted by the United States Golf Association (USGA) and The Royal and Ancient Golf Club of Saint Andrews, sets forth certain requirements for a golf club head. The requirements for a golf club head are found in Rule 4 and appendix 11. A complete description of the Rules of Golf are available on the USGA web page at www.usga.org. Although the Rules of Golf do not expressly state specific parameters for an insert for a putter, the Rules of Golf have been interpreted to establish that an insert for a putter should have a Shore A hardness greater than 87xc2x12%, have a constant thickness, have a thickness of at least 0.125 inches, and not act like a spring.
The prior art is absent a golf club head that has an insert composed of a material that is soft, but above the USGA requirements, and has a sufficient Bayshore rebound to provide a golf ball with the necessary distance to reach the hole.
The present invention provides a golf club head with an insert that is composed of a soft material yet has a good Bayshore rebound and a low tan. The present invention is able to accomplish this by using a material composed of a polyurethane formed from the reaction of at least one diisocyanate prepolymer and a curing agent.
One aspect of the present invention is a golf club head including a main body with a front face and a recess therein, an insert, an isolation layer and a weight body. The insert is disposed within the recess and is composed of a thermoset polyurethane having a shore D hardness in the range of 42 to 55, and a Bayshore rebound in the range of 50 to 70.
The thermoset polyurethane may be formed from a p-phenylene diisocyanate (PPDI)-based polyurethane prepolymer and a curing agent. Alternatively, the thermoset polyurethane may be formed from a toluene diisocyanate (TDI) based polyurethane prepolymer and a curing agent. Further, the thermoset polyurethane may be formed from a TDI-based polyurethane prepolymer, a PPDI-based polyurethane prepolymer, and a curing agent. The PPDI-based polyurethane insert has a lower tan xcex4 value. The tan xcex4 value measures the amount of energy a material loses as heat upon a high distortion or impact event (i.e. hysteresis).
Another aspect of the present invention is a golf club head including a club head main body having a recess therein, an insert disposed within the recess, an isolation layer composed of a thermoplastic polyurethane and weight body composed of tungsten. The insert is composed of a thermoset polyurethane formed from a PPDI-terminated polyester prepolymer in an amount up to 90 parts, a PPDI-terminated polyether prepolymer in an amount up to 90 parts, 10 to 40 parts of a TDI polyurethane prepolymer, and at least one curing agent. The curing agent is selected from the group consisting of a diol, a mixture of diols, a triol, a mixture of triols, a hydroquinone, a mixture of hydroquinones, a diamine, a mixture of diamines, an oligomeric diamine, and any mixture thereof.
Yet another aspect of the present invention is a golf club head that includes a main club head body with a front face and a recess therein, an insert, an isolation layer and a weight body. The club head main body is composed of a carbon steel and includes a front face, a toe wall to one side of the front face and a heel wall to the other side of the front face, and a sole. The front face has a recess therein for the insert. The insert is composed of a polymer material that has a shore D hardness in the range of 42 to 55, and a Bayshore rebound in the range of 50 to 70.
Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.